Background: Systematists have long questioned whether the thrush genus
Platycichla should be recognized as distinct with respect to the large
and cosmopolitan genus Turdus. For example, Ridgely and Tudor
(1989) noted that Platycichla was named solely because it is smaller
than most Turdus, and suggested that the two genera should probably
be merged considering their similarities in plumage, vocalizations, and
behavior.

New data and analysis: Two recent phylogenetic studies based on
mitochondrial DNA sequence data demonstrate conclusively that Platycichla is
nested within the genus Turdus, implying the two genera should be merged
in order to make Turdus monophyletic. Based on complete cyt b and
ND2 sequences, Klicka et al. (2005) found that Turdus is paraphyletic
but forms a well supported clade with the addition of three mostly monotypic
genera (Platycichla, Nesocichla, and Cichlherminia).
Although Platycichla was clearly found to be nested within Turdus, its
exact phylogenetic position was not determined owing to sparse taxon sampling;
in addition, only one of its constituent species (P. leucops) was
sampled. Voelker et al. (2006) presented analyses of cyt b, ND2, and ND3
sequences with much more complete taxon sampling: they included 60 of the 65
species of Turdus, in addition to the two species of Platycichla,
and several other thrush genera whose systematic position had been contentious.
Their results confirmed those of Klicka et al., showing that Turdus is
not monophyletic with respect to Platycichla: the two species in the
latter genus are part of a well-supported clade formed by mostly South American
Turdus taxa. Voelker et al. further showed that the two species of Platycichla
are not each other's closest relatives; a tree forcing the monophyly of the
genus was significantly less likely than unconstrained trees. The latter result
is consistent with differences in nesting biology between the two species noted
by Londo–o (2005).

Recommendation: I believe the available data leave no doubt that Platycichla
is not a distinct genus with respect to Turdus and that it is
not even a monophyletic group. Thus, I recommend a YES vote to get rid
of Platycichla and to rename its two constituent species as Turdus
leucops and T. flavipes. (Because Turdus has priority over Platycichla,
the latter genus needs to be eliminated.)

Comments from Remsen: "YES. Clearly, burden-of-proof now falls
on anyone claiming that Platycichla is not embedded within Turdus."

Comments from Stiles: "YES. The various citations clearly
indicate that Platycichla cannot stand as a genus unless one splits up Turdus into
an uncertain number of mini-genera, which would serve no useful purpose for
elucidating relationships. Also worth noting that unless I'm mistaken, only one
of the two species of Platycichla has been sequenced and there is thus
no explicit evidence that the two are sister species in any case."

Comments from Jaramillo: "YES - Data are clear that Platycichla
is nested within Turdus. Also, results in Voelker et al. 2007 show that Platycichla
flavipes and P. leucops are not sisters."

Comments from Robbins: "YES. Recently published molecular data
demonstrate that Platycichla is embedded within Turdus; hence, I
vote yes for subsuming this genus within Turdus."